Air screen door



E. J. KUREK AIR SCREEN DOOR Oct. 11, 1960 7 Sheets-Sheet 1 Fi1ed-Ju1y26, 1957 .INVENTOR. eiwz M Oct. 11, 19 E. J. KUREK 2,955,521

AIR SCREEN DOOR 7 Filed July 26, 1957 '7 Sheets-Sheet 2 IN V EN TOR.

BY WMVM a l l l l E. J. KUREK AIR SCREEN DOOR Filed July 25, 1957 I NVEN TOR.

Oct. 11, 1960 E. J. KUREK 2,955,521

AIR SCREEN DOOR Filed July 26, 1957 7 Sheets-Sheet 5 75 go 77 76 J0INVENTOR.

Oct. 11, 1960 E. J. KUREK 2,955,521

AIR SCREEN DOOR Filed July 26, 1957 7 Sheets-Sheet 6 INVENTOR.

E. J. KUREK AIR SCREEN DOOR Oct. 11, 1960 7 Sheets-Sheet 7 Filed July26, 1957 a E 7 8 I a 0 use 4 w 1., r 9 9 k ll 4. w q r 0 3 M M w s f A A9 n 9 9 mmvm.

2,955,521 1 AIR SCREEN noon Edwin J. Kurek, New Castle, Ind.-, assignorto New Castle Products, Inc., New Casfle, Ind., a corporation of Indiana1 Filed July 26, 1951,'s...No.-6 4,;vs J

14 Claims. 01. 98-36) The present invention is directed to a new andimproved air door structure which makes use of air screen forrndischargecontrol portion of new and improved .structural arrangement andoperational efficiency.

Commercial use of air doors of the type providing for a continuouslymoving screen or barrier of air capable of efiiciently closing 01f apassage-type entrance has recently become feasible in light of improvedforms of air operation in defining and controlling the effective airscreen. in an automatic manner to compensate for variations in internaland external conditions of the type affecting efficiency of use of theair screen.

Other objects not specifically set forth will become apparent from thefollowing detailed description made in conjunction with the drawingswherein:

Fig. 1 ,is a fragmentary perspective of an improved form. of air screendoor structure making use of the new flow control equipment. Air doorsof the type now found in use provide means whereby air is continuouslyrecirculated at a suflicient velocity and in a regulated manner toprovide for a substantially impregnable air screen capable of closingoff a building opening in the form of' a door structure to an extentthat movement of inside or outside air or foreign material through thescreen is prevented while allowing full and uninterrupted use of..thedoor structure for ingress and egress of customers or inhabitants. Acontinuously moving screen of air creat s, in effect, an invisible wallwhich is capable of preventing penetration of outside air, foreignmaterial such :as dust, dirt or debris, insects and even snow,rain,;or;mnd. '-';'l."he screen is of such a nature that, upon passingtherethrough,

the individual is not personally disturbed =by.air5contact. I

.Many advantages arise from the use ,of an 'airscreen door of the typedescribed, some of these advantagesbeing for example: the elimination ofswinging "or revolving ldoorv structures requiring manipulation by theuser and further resulting in a bottleneck insofar i as :full capacityuse of the door area is concerned; elimination .of wind gusts oftenresulting from the use of a single swinging door structure; eliminationof double door structures,

with intermediate wasted vestibule space for windproofing purposes;reduction in door structure space; and advantageous use of added displayspace arising from the transparent nature of the air screen.

It is an object of the present invention to provide a new and improvedform of air screen door structure including therein air moving andcontrolwequipment of unitized construction providing for efficient,uncomplicated, low cost door installation while providing automaticvariable operation with little accompanying .upkeep.

A further object is to provide a unitized assembly of air moving andcontrolling equipment capable of prefabrication in the form ofseparatejreadily'combinable'units whichare readily assembled in theiroperative positionton the job site with a minimum of expense and effort;the unitized assemblies constituting the air movingfandcontrollingequipment of the door structure including ;a particularly efficient formof air movingtand conditioning arrangement which in and of itselfconstitutes a part of the present invention; the overall unitizedassembly:lure

of the present invention;

Fig. 2 be partially diagrammatic illustration in end elevation of theimproved air moving and control assembly in its operative position inthe door structure; Fig. 3..is .a front elevation of the assembly ofFig. 2, theassembly being diagrammatically illustrated as viewed fromthe right in Fig. 2;

Fig.4 is an'end elevation of the frame structure of a prefabricated unitforming a part of the improved air moving and control assembly of thepresent invention; Fig. 5 is a front elevation of the frame of Fig. 4;Fig. 6 is a top plan of the frame of Fig. 4;

Fig. '1 is a top plan of a unitized blower and motor assembly designed:for mounting in the frame of Figs. 4-6; Fig.3 is an end elevation ofthe assembly of Fig. 7; Fig. 9 is a front elevation of the assembly ofFig. 7; Fig. 10 is an end elevation of an air flow control andconditioning prefabricated unit constituting a part of the presentinvention;

Fig. 11 is a front elevation of the unit of Fig. 10; Fig. 12 is anopposite end elevation of the unit of Fig. 11;

. Fig. 13 is a rear elevation of the unit of ,Fig. 11; Fig. l4-is a topplan of the unit of Fig.'1l; I

Fig. 15 is a partially schematic vertical section .of an airdistributing and discharge control unit forming a part of the assemblyof the door structure of the present invention; I I

. Fig. 16 is aview similar ,to Fig. 15 tion of the assembly thereof;Fig. 17 is another view similar to Fig. 15 illustrating and improvedunitized air moving and control assembly illustrating operastill furtheran operational aspect of the unit thereof; 7 Fig. :18 is anenlargedfragmentary perspective of. a

portion of thevai-r distributing and discharge control unit of Fig. 15;and v Fig. 19 is an enlarged Fig; 15.

in Fig. 1 an air screen .door structure including the improved unitizedair moving and controlling assembly of the present invention isillustrated as being defined by an elongated rectangular opening 25formed from parallel side walls 26 and 27, a grate defining floor 28 anda ceiling 2s. The side wall 26 is coextensive with the opposite sidewall 2.7 and is constructed as an inwardly extending Wall portion formedwith the outer wall 30 of a store front which may include windowsections 31. The grate 28 defines a portion of the top of a rectangularpit 32 which is of a width equal to the grating 28 while being in lengthequal to the width of the entire door structure. The pit 32 defines anair return chamber from which air is drawn by a prefabricated, unitizedair moving and conditioning assembly mounted behind the side wall 27 andenclosed at the inner end as viewed in Fig. l by top plan view of theunit of a wall partition 33.

The air moving and'conditioning assembly is vertically arranged behindthe side wall 27 and wall partition 33 ther including anairrdistributing. and dischatge control assembly of new anclimproveddesigncapable of eflicient and access panels '34,. 35 and 36 areremovably mounted in the central portion of. the side wall 27 fordismounting for access to the air moving and conditioning assembly forma intenance thereof. Theceiling Z9 defines the .bot

Patented Get. 11, 1360 is introduced by the air moving and conditioningassembly housed behind the wall partition 33 into the plenum area behindthe wall section 37 and downwardly through the ceiling 29 in acontrolled manner by means of an air distributing and discharge controlassembly 38 housed in the ceiling 29. Air is moved at a relatively highvelocity downwardly between the side walls 26 and'27 in a controlledmanner to define a transversely extending air screen, the air movingthrough the grating 28 and into the pit 32 for recirculation within thedoor structure.

As particularly shown in Figs. 2 and 3, the pit 32 is located below thefloor line 39 with which the grating 28 is level and may be in theformofv a poured concrete basin or chamber being provided with an inclinedbottom wall 40. Near the upper end of the bottom wall 40 is positioned aspray pipe 41 provided with a plurality of water directing nozzles 42arranged to sweep or clean the bottom wall 40 in a direction toward adrain 43 extending through the bottom wall 40 as the lowest end thereof.A suitable water supply pipe 44, partially shown in Fig. 3, is connectedwith the spray pipe 41 to provide water thereto for flushing the pit 32and removing therefrom debris, dirt and other foreign matter which fallsthrough the grating 28 and is collected on the bottom wall 40. As shownin Fig. 3, an automatic timer 45 is electrically connected to anautomatic valve structure 46 to provide for periodic operation of thespray assembly at predetermined time intervals. With this arrangementthe interior of the pit 32 is periodically cleaned in an automaticmanner as determined by the extent to which the air screen structure isused.

As particularly shown in Fig. 2, the air moving and conditioningassembly housed by the side wall 27 and positioned to one side of thedoor structure opening 25 includes -a pair of prefabricated orpreassembled, separate units 47 and 48 which function to provide forcontinuous air movement in a substantially circular manner through thedoor structure as indicated by the arrows. Generally speaking, thelowermost unit 47 functions as an air moving unit by reason of includingan air blower 49 of known design being belt-driven by'an underslungmotor 50. The outlet opening of the blower 49 is connected With a duct51 by a flexible and expandable flexible duct 52, the duct 51 forming apart of the air delivery and conditioning unit 48. This latter unitincludes an outer duct 53 which is, in essence, wrapped'around an airheating unit 54 having in communication therewith a separate inlet ductmeans 55 for delivering air thereinto'. The air heater 54 is providedwith a venting stack 56 in a manner to be described and air is deliveredthrough the duct 53 and heater 54 into the plenum area 57.- The bottomsurface of the plenum 57, as previously described, is defined by theceiling 29 which carries the air distributing and discharge controlassembly 38 through which the air is controllably discharged in adownwardly direction across the door structure opening 25 andsubsequently through the grating 28 into the pit 32 for recirculation.

The units 47 and 48 of Fig. 2, as previously described, areprefabricated units each of which is separately assembled at the factoryand shipped to the job site. At the job site the shipping packing ofeach unit is removed and the unit 47 is installed in the preconstructedside wall cavity of the door structure with the unit 48 beingsubsequently installed on top of the unit 47 in stacked relation and theblower 49 being interconnected with the duct 51 by means of the flexibleduct 52. With this arrangement, installation costs are maintained at aminimum and each of the units 47 and 48 is of compact design so as torequire only a relatively small area for mounting in their operativepositions. No special structural framework or supporting beams need beinstalled at the job site, it being necessary merely to preconstruct thewall cavity into which the air moving and conditioning assembly is to beinstalled in accordance with the dimensions of the same which arereadily obtainable from the manufacturer.

Figs. 4-9 illustrate in detail the structural features of the blowerunit 47. This unit includes a frame 58 which as shown in Figs. 4-6 is ofrectangular, box-like shape. The frame 58 includes four vertical cornerposts or vertical supports 59 interconnected at their top and bottomends by horizontally extending side beams 60. The lowermost side beams60 are arranged to support within the frame 58 filter pads 61 which, asshown in Fig. 2, cover the opening of the pit 32 through which air isdrawn into the air moving and conditioning assembly behind the side wall27. In this manner air drawn upwardly for recirculation through the dooropening 25 is filtered prior to conditioned delivery into the plenumarea 57.

Slightly above the lowermost side beams 60 are a series of rectangularlyarranged reinforcing side beams 62 which are interconnected with thecorner posts 59 as particularly shown in Fig. 6. The reinforcing sidebeams 62 support therebetween a pair of spaced channel bar supports 63which at the'ends thereof are provided with drilled holes 64. As shownin Figs. 7-9, plates 65 support therebetween intermediate the endsthereof the blower 49 on platform beams 66 which are suitably attached,as by welding, at their ends to the plates 65. Spaced, vertical blowersupporting flanges 67 extend upwardly from the beams 66 and are suitablyattached to the blower 49. The blower 49 is provided with an operatingshaft 68 carrying a multi-groove pulley 69 thereon which is drivinglyconnected to a multi-groove pulley 70 by a plurality of belts 71. Thepulley 70 is journalled on the drive shaft 72 of the electric motor 50which is suitably attached to the bottom surfaces of the transversesupporting beams 66 in an underslung position.

The blower motor assembly, as shown in Figs. 7-9, is mounted in theframe 58 by shock absorbing elements 73 which are carried at the ends ofthe plates 65. The plates 65 are received within the frame 58transversely of the plates 63 with the bottom surfaces of the shock absorbers 73 being suitably bolted through the holes 64 therein. Thismounting arrangement of the blower assembly within the frame 58 is bestillustrated in Fig. 2. The compact structure provided by thisarrangement is particularly adapted for prefabrication and subsequentspeedyinstallation upon delivery to the job site. The blower 49 is ofconventional design being provided with a suitable'air moving element inthe form of a fan which may be of the squirrel cage variety rotatablyoperated by the shaft 68 which is driven by the motor 50. The motor 50will preferably be a single speed motor in the interest of economy ofconstruction and maintenance with adequate air flow control beingafforded by the assembly 38, the structural features of which will besub sequently described.

The structural details of the prefabricated unit 48 are particularlyshown in Figs. 10-14. A structural frame is defined by four bottom beams74 which are rectangularly arranged for resting engagement with the fouruppermost side beams of the structural frame 58 of the unit 47. Thedischarge side of the unit 48 is defined by a pair of spaced, verticallyextending posts 75 which at the tops thereof are interconnected by atransverse angle iron beam 76 and which intermediate the ends thereoftoward the center thereof are interconnected by a transverse beam 77which defines the location of the ceiling 29 of the door structure. Theuppermost ends of the po'sts75 are interconnected with the rearmost endsof the bottom beams 74 by a pair of diagonally directed supports 78..The vertical posts are further interconnected to the diagonal supports78 by horizontally extending braces 79.. v

Theair intakeduct portion 51 is in communication with a duct 53 aspreviously described, this duct being formed from interconnected,vertically extending inlet ductand right angled horizontally extendingoutlet duct portions the latter of which opens outwardly of the frontface oft he 'unt as defined by the vertical beams 75. AS

particularly shown in Figs. 11 and 14, the outlet end of the duct 53 issubdivided into separate segments 80 from which air flows into the.plenum area 57 as previously described. Intermediate the duct segments80 a flue chamber 81 is located throughwhich the stack 56 extends forexhausting flue gases from the unit 48, the stack 56 being of suflicientvertical height to extend outwardly from the building in which the airscreen door is installed. i

Immediately below the duct segments 80is'positioned an air heating unit54' whichincludes a pair of air heating chambers 82 of: anysuitabletypbeing provided with a plurality of vertically directed fins83ibetween which air flows outwardly into the plenum areaalong an areabelow the outlet openings of'the duct segments 8 01 The air chambers 82'are at'l'east partially divided by the flue chamber 81. The air heatingchambers 82 have positioned therebelo'w a plurality of gas burners .84of a well known type which are operated through a gas line 85 connectedto a suitable source in the building. The gas burners 84 are suitablycontrolled in operation by a known type of automatic equipment whichdoes not form a part of the present invention. Gas burner main controls86 are accessible immediately inwardly of the access panel 36 asparticularly shown in Fig. 2 for maintenance and seasonal adjustmentpurposes. The air heating unit 54 'is supported between the horizontalbeams 79 by a pair of transverse beams 87 as particularly shown in Figs.12 and 13. Air is delivered into the heating chambers 82 by the ductportion 55 previously described which is in communication with the ductinlet'portion 51 as particularly shown in Fig. '2.

The operation of the air moving and conditioning unit 48' is bettershown in Fig. 2 wherein the ducts 53 and 55 are illustrated as includingpivotal dampers 88 and 89, respectively, which are movable to controlthe amount of air passed through the duct 55 toward the heating unit 54.The dampers 88 and 89 are each carried by pivotal rods 90'which can besuitably operated by known thermostatic controlequipment' to provide-therequisite degreeof air temperature for the screen directed downwardlythrough the-door opening 25.. I In colder weather operation, asubstantial amount of the circulating air. will be passed throughtheheating unit 54 to maintain the airscreen at a comfortable temperaturefor contact with individuals passing therethrough into or out of thebuilding; The dampers 88' and 89 are set to prevent the exceeding ofthe. maximum volume of air flow through the heaters in line with therated capacity'of the same. While operation of thedampers bythermostatic control equipment may be used, it may be found preferableto fixedly set the dampers for rated maximum airflow control'andmaintained air temperature at the desired level by automatic cyclefiring of the burners through a separate thermostat controlling anelectric solenoid'feed'ing gas directly to the burners. The duct 53functions, in effect, as a by-pass duct which passes that air which isnot being heated around the heating unit 54. The right angled change indirection of travel of the air through the duct 53 is con trolled by aplurality of turning vanes 91 carried therein as particularly shown inFig. 2.

The particular arrangement described whereby the duct 53 is, in effect,wrapped around the heating unit 54 provides for .a compact designcapable of highly efiicient use and further, particularly adapted forprefabrication into a single unit for shipping and subsequentinstallation. A11 available space isefliciently used: within theframework of the unit 48; Furthermore, heating efficiency is maintainedat a maximum particularly where. substantially all of therecirculatedhairis .heatedduring cold weather operation of the aircurtain door. .The duct=53 extendingabov'e the heating unit 54 is, inefiect, in indi-' rect heat-exchangerelation therewith thus resulting inat leastuaslight heating .of the air by-passed therethrough gri to intod ction intothe plea-nuance 57. Further.-

more, the flue gas chamber 81 extends upwardly between the duct segmentsand the flue gas is,in effect, in in direct heat exchange relation withthe interior of the duct segments 80. Thus the compact design of the airmoving andconditioning unit 48 provides for ,elhcient utilization ofheat in not only directly heating passed through the heating unit 54 butfurther establishing indirect heat exchange relation with air by-passedthrough the. duct 53;.

Fig. 1 illustrates the access panel 35 as carrying a removable cover 92which, when detached, exposes. suitable controls for regulating suchoperations as. the periodic flushing of the ph 32. in. the mannerpreviously described, all of the various automatic controls. used in thedoor as sembly being of a known type capable of providingauto matio dooroperation. Y

Figs. 15-19 illustrate in detail the air distributing and dischargecontrol assembly 38 which is mounted in the ceiling 29 of the doorstructure: This assembly constitutes an important part of thepresent'invention in that it is relatively simply constructed withlightweight de sign and capable of highly e'fiicient operation incompensating for changing weather conditions which affect efiicient useof the air screen in separating the interior and exterior of thebuilding, Referring first to Fig. 19, the assembly 38 is formed from arectangular frame 94 which is suitablyreceived within the ceiling 29 ofthe door structure and which may be hingedly attached thereto along oneside for downward swinging movement to. allow access thereto formaintenance or access into the plenum area 57 when desired. The frame 94supports a plurality of spaced, bar-like members 95 which form a gratethrough which air passes in a downward direction; Each of the bar-likemembers 95 is provided with a horizontally flat bottom surface and aconvex top surface. These members may be formed in any suitable mannerand, 'as illustrated, maybe fabricated from-channel strips 96 into thetop openings of which are received a-rcuate metal strips 97, thesestrips being suitably attached to one another such as by welding.

To each side of the series of bar-like members 95 is a plate 98enclosing the 'end portions of the frame94 adjacent the exit andentrance areas of the door opening 25. Opposite ends of the frame 94carry vertical mount ing plates 99 which journal therethrough the endsof a pair of pivotally mounted'rodsltlt). Each of the rods.

ltlll has attached at anendt'hereof a pulley 101 about which is receivedacable 102' which is guided into engagernent with the pulleys 101 bya'series of grooved guide rollers 103. The single cable 102'is'attached' -at one of its ends to a flat bar 164 attached to the end"of a. reciprocating piston'rod 105 forming a part of a'known type ofpressure differential responsive mechanism 106. This mechanism includesa servo-motor which operates the rod 105. The remaining end of the cable102 is attached to an end of bar 104- in such a manner that, uponmovement of the piston rod 105, the cable 162 will remain taut about thepulleys 101 and guides 103 topivot each of the rods 1% in oppositedirections.

Attached to each of the rods is an arcuate vane 107, the pair of vanesbeing better shown in Figs. 15-47. Spaced bars 108 are suitably attachedat their ends to a vane 107 and at their remaining ends to an adjacentpivotal rod 100 to pivot the vanes in a vertical direction above andthrough the frame 94. The length of the bars 108 is equal to theradiusof the arc of movement of the vanes 167 relative to the centers ofthepivotal rods 100,

7 this radius being equal tothe distance from the rods 100 curvature ofeach vane 107 coincides with the'arc described during movement of. thesame to permit free I movement of each vane .107 through the frame 94.Thetion (extending through the frame 94) is concave for a purpose to bedescribed.

In the operation of air doors, it is essential to provide means wherebythe direction of downwardly moving air current defining the curtain canbe redirected to compensate for changing external or internal pressurecondi tions which -might cause breaching or partial destruction of air'screen. Figs. 15-17 diagrammatically illustrate the manner in which thevanes 107 regulate the direction of flow of air stream through theassembly 38 to compensate' for variations in weather conditions.Referring first 'to Fig. 17 where airpressure externally of the doorstructure is at'least substantially equal, to internal building airpressure, no control of the downwardly directed air current defining theair screen is necessary and air flow is vertically 'downwardly throughthe assembly 38 in the direction of the arrows 109. With no directionalcontrol being required, the vanes 107 are held in their inoperativepositions which constitute location of the vanes above the frame 94.

In the event of greater air pressure externally of the building, an aircurrent illustrated by the arrows 110 in Fig. 16 will tend to passthrough the door structure and through the air screen exemplified by thearrows 111 in Fig. 16. Under these circumstances, the air current 110has a tendency to penetrate the air curtain 111 if suitable directionalcontrol of the latter is not utilized. In order to prevent external aircurrent penetration, the right hand vane 107, which is the outermostvane as described in connection with Fig. 15, is moved into a downwardlyprojecting position relative to the frame 94. The outer concavesurfaceof the vane 107 causes the formation of an area of vacuum which resultsin the drawing of the air currents 111 defining the air screen to theright, as viewed, toward the incoming air currents 110. With thisarrangement, the force of the downwardly flowing air screen is directedsufficiently toward the inwardly flowing air currents to counteract thesame and prevent penetration of the air screen. With the downwardpositioning of the outermost vane 107 as viewed in Fig. 16, theinnermost or opposite vane 107 is automatically moved upwardly above theframe 94 into a completely inoperative position. Single cable operationof both of the vanes 107, as previously described in connection withFig. 18, causes both to move at the same time to provide relativepositioning described. While single cable operation is disclosed, itwill be understoodthat dual cable or separate vane operation is intendedto fall within the scope of the present invention;

Fig. 15 illustrates operation of the assembly 38 in the event of agreater internal pressure in the building, such as would be caused byfan operation or air conditioning, which results in air currents 112attempting to penetrate the air screen 113 by moving through the sametoward the exterior of the building. In order to counteract the internalair currents 112, the innermost vane 107 on the left as viewed in Fig.15 is lowered into its operative position below the frame 94 to form avacuum pocket and cause the air curtain 113 to flow substantially towardthe left as viewed. The oppositely positioned or external vane 107 is,under these circumstances, raised into a completely inoperative positionabove the frame 94.

To provide automatic control operation of the air distributing anddischarge assembly 38 in response to variations in internal or externalpressures relative to the door structure, a static pressure differentialcontrol system including the mechanism 106 is used to determine thedilferential pressure existing between the pressures on each side of theair screen. Such control systems are well known and their structuralfeatures per se do not constitute a part of the present invention. Anysuitable static pressure control system can be mounted relative to theair moving and conditioning assembly behind the side wall; .27. of thedoor structure in operative connection with the mechanism 106 of theassembly'38.' By way of example, flexible tubing may extend frompressure communication taps to the mechanism 106. As illustrated in Figs1 and 3, static pressure taps or measuring openings 114 are preferablycarried in the top access panel 36 to either side of the air screenmaintained within the door opening 25. Pressure differential between thetwo points 114 is automatically and continuously measured and theservo-motor forming a part of the, mechanism 106 operates in response topredetermined differential to move the vanes 107 into or out of theiroperative positions and thus compensate for pressure differ ential'bycontrolling the direction of flow of the air curtain. The staticpressure difierential taps 114 are pref e'rably positioned immediatelybelow the ceiling 29 where the air currents defining the air curtain aremost effective by reason of their velocities being the greatest in thisarea. Due to the highest velocities existing at the defining area of theair curtain, the differential pressure built up on either side of the'same will be the greatest and such differential pressure shouldpreferably be measured within this area. Variations in location of thepressure measuring taps 114 can be made and, for example, an alternatetap location 115 is illustrated in Fig. 1 as being in the ceiling 29 oneither side of the assembly 38. The location of the taps within the doorstructure as, for example, along the side wall 27 or ceiling 29, ispreferred in order to protect the same from the deleterious effect ofoutside weather conditions.

As illustrated in Figs. 18 and 19, movement of the piston rod outwardlyof the housing of the servomotor of the mechanism 106 would cause thevane 107 on the left, as viewed in Fig. 19, to move downwardly throughthe frame 94 into its operative position. By. use of the single cable102, the opposite vane 107 (not illustrated in Fig. 19) would be raisedto its inoperative position above the frame 94. Withdrawal of the pistonrod 105 into the housing of the mechanism 106 would result'in reverseoperation of the vanes 107. With equal ized internal and externalpressure conditions relative to the door structure, the position of thepiston rod 105 will be such that each of the vanes 107 areinoperatively'positioned as illustrated inFi'g. l7.

From the foregoing description it will be apparent that a double doorstructure can be readily obtained by utilizing oppositely positioned airscreen forming units. In other words, a complete assembly similar tothat described can be mounted on the opposite side of the door structurewhich, as illustrated is defined by the wall 26, and the door structurewill, in effect, be doubled in width. The provision of the side wall 26in connection with the use of a single air screen producing assembly asillustrated is essential to maintain etficient establishment of the airscreen. That portion of the side wall 26 which the air screen contactsin its downward movement provides a surface which the air currentfollows and by which it is con-' trolled to establish an uninterruptedor unbroken fiow of air capable of preventing the passage of foreignmatter,- such as dirt, rain or snow, therethrough. The side wall 26 canbe of any solid construction adjacent the air screen area.

The velocity of the air delivered downwardly through the door structurewill be in the neighborhood of 2,000 feet per minute and in providingthis air velocity in the type of assembly described, the motor used maybe a relatively inexpensive, one speed 5 H1. unit. While the motor hasbeen previously described as a single speed unit, it will be understoodthat a multi-speed unit can be used to provide a further means forcontrolling the effectiveness of the air screen with changing externaland interal pressure conditions.

With automatic operation of the assembly as described, practically noupkeep or maintenance is necessary with the exception that the filters61 must be periodically removed; cleaned orreplaced. The access panels34, 35 and-36.

can be readily removed for this purpose or for any other maintenancepurpose. Other types of air heating units can be utilized if desired, itbeing understood that a gas heated unit has been described merely forpurposes of illustration. The floor grating 28 may be of any knownstructural arrangement, such gratings being frequently used in buildingstructures. During cold weather, the use of heated air in forming theair screen will not only retain building heat but will further preventsnow or' ice accumulation on the grate 28.

wObviously many modifications and variations of the invention ashereinbefore set forth may be made without depart-ing from the spiritand scope thereof, and. therefore only such limitations should beimposed as are .in-. dioated in the appended claims.

Iclaim: f

1. An air screen door structure having an inner air screen dividedpassageway defined by top,- bottom and side walls, said bottom wallincluding a floor grating which defines the top of an air return chamberforming a part of said structure, said top wall having mounted thereinan air control delivery assembly which defines the bottom of an airdelivery chamber forming a part of said structure, at least one of saidside walls enclosing an air moving and conditioning assembly incommunication with said air return and air delivery chambers and whichis formed from a pair of sectionalized prefabricated units one restingon the other in stacked relation, the lowermost of said units beingformed from a frame structure which supports air moving means fordrawing air from said air return chamber and delivering the sameupwardly into the uppermost of said units, said uppermost unit beingformed from a frame structure which supports an air conditioning and airflow control means for delivering air into said air delivery chamber forforced air flow downwardly therefrom through said passageway. I

2. An air screen. door structure having an inner air screen dividedpassageway defined by top, bottom and side walls, said bottomwallincluding a floor grating which defines the top of an air return chamberforming apart of said structure, said toptwall having mounted therein anair .control' delivery assembly which defines the bottom of anairdelivery chamber forming a part of said structure, said air controldelivery assembly comprising a frame-like structure; in the form of'agrate provided with,a pluralityof spaced bar-like members past which airis moved downwardly and by which; air is distributed, vanes movablymounted on said framelike structure'along opposite sides thereof forvertical pivotal movement thereof relative to said bar like mem berthrough said air control delivery assembly into a downwardly positionprojecting into the interior of said passageway, each of said vanesbeing in the form of a' solid panel of arcuate shape the outermostsurface of which is concave, means for pivoting said vanes, at least oneof said side walls enclosing an air moving and conditioning assembly incommunication with said air return and air delivery chambers and whichis formed from a pair of sectionalized prefabricated units one restingon the other in stacked relation, the lowermost of saidunits beingformed from a frame structure which supports an air moving means fordrawing air from said air return chamber and delivering the sameupwardly into the uppermost of said units, said uppermost unit beingformed from a frame structure which supports'an air conditioning and airflow control means for delivering air into said air delivery chamber forforced air flow 7 which defines the top of an air return chamber forminga part of said structure, said top wall ,having- 'niountcd therein anairc0ntrol delivery assembly which defines id the bottom of an airdelivery chamber forming a part of said structure, said air controldelivery assembly comprising a frame-like structure in the form of agrate provided with a plurality of spaced bar-like members past whichair is moved downwardly and by which air is distributed, vanes movablymounted on said frame-like structure along opposite sides thereof andpositioned transversely of said side walls for vertical pivotal move:ment through said frame-like structure relative to said bar-like membersinto a downwardly position projecting into said passageway, each of saidvanes being in the form of a solid panel of arcuate shape the outer,surface of which is concave, and operating means for said vanesincluding spaced pressure sensitive means positioned on each side of thearea of downwardly moving air along a side wall of said passageway nearvthe top wall thereof, said pressure sensitive means measuring pressuredifferential within said passageway for operational control of saidoperating means, at least one of said side walls enclosing an air movingand conditioning assembly in communication with said air return and airdelivery chambers and which is formed from a pair of sectionalizedprefabricated units one resting on the other in stacked relation, thelowermost of said units being formed from'a frame structure whichsupports air moving means for drawing air from said air return chamberand delivering the same upwardly into the uppermost of said units,said-uppermost unit being formed from a frame structure which supportsan air conditioning and air flow control means for delivering air intosaid air delivery chamber for forced air flow downwardly therefromthrough said passageway.

4. An air screen door structure having an inner air screen dividedpassageway defined by top, bottom and side walls, said bottom wallincluding a floor grating which defines the top of an air return chamberforming a part of said structure, said top wall having mounted thereinair control delivery assembly which defines the bottom of an airdelivery chamber forming a part of said structure, atr'least one of saidside walls enclosing an air moving and conditioning assembly incommunication with said air return and air delivery chambers andwhichhis formed from a pair of sectionalized prefabricated unitsone-resting on the other in stacked relation, the lowermost of saidunits being formed from a frame structure which supports air movingmeans for drawing air from said air return chamber and delivering thesame upwardly into the. uppermost of said units, said uppermost unitbeing formed from a frame structure which supports therein separate setsof inlet duct means and outlet duct means which duct means of each setare interconnected at substantially right angles to one an: other, oneof said sets being nested in the other, air heating means interposed inone of said sets to heat a pre determined quantity of air passedtherethrough, air being discharged from said outlet duct means into saidair delivery chamber for forced air flow downwardly therefrom throughsaid passageway, and fine means forming a part of said air heating meansand extending therefrom and through said outlet duct means in indirectheat exchange relation with air moving therethrough,

5. An air screen door structure having an inner air screen dividedpassageway defined by top, bottom and side walls, said bottom wallincluding a floor grating which defines the top of an air return chamberforming a part of said structure and including therein meansforperiodically flushing foreign matter therefrom, said top wall havingmounted therein an air control delivery assembly which defines thebottom of, an air delivery chamber forming a part of said structure,said air control delivery assembly comprising a frame-like structure 'inV the form of a grate provided with aplurality of spaced .on saidframe-like structure along opposite sides ther'eof transversely of theside walls of said passageway for vertical pivotal movement through saidframe-like structure relative to said bar-like members into a downwardlyposition projecting into said passageway, each of said vanes being inthe form of a solid panel of arcuate shape the outermost surface ofwhich is concave, means for pivoting said vanes, at least one of saidside walls enclosing an air moving and conditioning assembly incommunication with said air return and air delivery chambers and whichis formed from a pair of sectionalized prefabricated units one restingon the other in stacked relation, the lowermost of said units beingformed from a frame structure which supports air moving means fordrawing air from said air return chamber and delivering the sameupwardly into the uppermost of said units, said uppermost unit beingformed from a frame structure which supports therein separate sets ofinlet duct means and outlet duct means which duct means of each set areinterconnected at substantially right angles to one another, one of saidsets being nested in the other, air heating means interposed in one ofsaid sets to heat a predetermined quantity of air passed therethrough,air being discharged from said outlet duct means into said air deliverychamber for forced air flow downwardly therefrom through saidpassageway, and flue means forming a part of said air heating means andextending therefrom and through said outlet duct means in indirect heatexchange relation with air moving therethrough.

6. An air moving and heating assembly of prefabricated design for use inan air screen door structure, said assembly including a structural frameof box-like shape supporting therein along two adjacent sides thereof aright angled duct structure which at one end is open for air intake andat the other end is longitudinally subdivided into two separate segmentswhich define a space therebetween and each of which at their outermostends defines an air discharge opening, a pair of transversely spaced airheating chambers supported by said frame substantially centrally thereofand in communication with said duct structure near the intake endthereof through separate duct means forming a part thereof, saidchambers each having an air discharge opening in closely spaced relationto the air discharge openings of said duct structure, heat supply meanscarried by said frame in association with said heating chambers, andflue means in communication with said heat supply means and extendingintermediate said heating chambers and said duct structure segmentsthrough said space in indirect heat exchange relation therewith.

7. An air moving and heating assembly of prefabricated design for use inan air screen door structure, said assembly including a structural frameof box-like shape supporting therein along two adjacent sides thereof aright angled duct structure which at one end is open for air intake andat the other end is longitudinally subdivided into two separate segmentswhich define a space therebetween and each of which at their outermostends defines an air discharge opening, a pair of transversely spaced airheating chambers supported by said frame substantially centrally thereofand in communication with said duct structure near the intake endthereof through separate duct means forming a part thereof, saidchambers each having an air discharge opening in closely spaced relationto the air discharge openings of said duct structure, air fiow controlmeans forming a part of the intake end of said duct structure and saidseparate duct means to control the dew of air therethrough, heat supplymeans carried by said frame in association with said heating chambers,and flue means in communication with said heat supply means andextending intermediate said heating chambers and said duct segmentsthrough said space in indirect heat exchange relation therewith.

. 8. Air distributing and discharge control means for use in an airscreen door structure, comprising a framelike structure in the form of agrate provided with a plurality of spaced bar-like members mountedtherein past which air is moved and by which air is distributed, vanesmovably mounted on said frame-like structure along opposite ends thereoffor movement therethrough relative to said bar-like members insubstantially parallel relation therewith, each of said vanes being inthe form of a solid panel of arcuate shape the outer surface of which isconcave, and means for moving said vanes.

9. Air distributing and discharge control means for use in an air screendoor structure, comprising a frame-like structure in the form of a grateprovided with a plurality of spaced bar-like members mounted thereinpast which air is moved and by which air is distributed, said bar-likemembers each having a flat bottom surface and a convex top surface,vanes movably mounted on said frame-like structure along opposite sidesthereof for movement therethrough relative to said bar-like members insubstantially parallel relation therewith, each of said vanes being inthe form of a solid panel of arcuate shape the outer surface of which isconcave, and means for moving said vanes.

10. Air distributing and discharge control means for use in an airscreen door structure, comprising a framelike structure in the form of agrate provided with a plurality of spaced bar-like members mountedtherein past which air is moved and by which air is distributed, vanesmovably mounted on said frame-like structure along opposite sidesthereof for movement therethrough relative to said bar-like members insubstantially parallel relation therewith, each of said vanes being inthe form of a solid panel of arcuate shape the outer surface of which isconcave, said vanes each being held at the top thereof by inwardlydirected arms which at their outermost ends are attached to rods mountedon said framelike structure for reciprocal pivoting, and means formoving said vanes.

11. Air distributing anddischarge control means for use in an air screendoor structure, comprising a framelike'structure in the form of a grateprovided with a plurality of spaced bar-like members mounted thereinpast which air is moved and by which air is distributed, vanes movablymounted on said frame-like structure along opposite sides thereof formovement therethrough relative to said bar-like members in substantiallyparallel relation therewith, each of said vanes being in the form of asolid panel of arcuate shape the outer surface of which is concave, saidvanes each being held at the top thereof by inwardly directed arms whichat their outermost ends are attached to rods mounted on said framelikestructure for reciprocal pivoting, and operating means for said vanesincluding a single cable and plural pulley arrangement interconnectedwith said rods for simultaneous raising of a vane on one side of saidframe-like structure while lowering an oppositely positioned vane.

12. In an air screen door structure having a through tunnel-likepassageway with said structure being provided with air moving meansarranged to continuously close said passageway by providing a screen ofdownwardly directed air, the provision in association with the ceilingof said passageway of an air distributing and discharge control meanswhich comprises, a frame-like structure in the form of a grate providedwith a plurality of spaced bar-like members mounted therein past whichair is moved downwardly and by which air is distributed, vanes movablymounted on said frame-like structure along opposite sides thereof forvertical pivotal movement therethrough relative to said bar-like membersin substantially parallel relation through into a downwardly positionprojecting into said passageway, each of said vanes being in the form ofa solid panel of arcuate shape the outer surface of which is concave,and means for moving said vanes.

13. In an air screen door structure having a through 13 tunnel-likepassageway with said structure being provided with air moving meansarranged to continuously close said passageway by providing a screen ofdownwardly directed air, the provision in association with the ceilingof said passageway of an air distributing and discharge control meanswhich comprises, a frame-like structure in the form of a grate providedwith a plurality of spaced bar-like members mounted therein past whichair is moved downwardly and by which air is distributed, said bar-likemembers each having a fiat bottom surface and a convex top surface,vanes movably mounted on said frame-like structure along opposite sidesthereof for vertical pivotal movement therethrough relative to saidbar-like members in substantially parallel relation therewith into adownwardly position projecting into said passageway, each of said vanesbeing in the form of a solid panel of arcuate shape the outer surface ofwhich is concave, said vanes each being held at the top thereof byinwardly directedarms which at their outermost ends are attached to rodsmounted on said frame-like structure for reciprocal pivoting, andoperating means for said vanes including a single cable and pluralpulley arrangement interconnected with said rods for simultaneousraising of a vane on one side of said frame-like structure whilelowering an oppositely positioned vane.

14. In an air screen door structure having a through tunnel-likepassageway with said structure being provided with air moving meansarranged to continuously close said passageway by providing a screen ofdownwardly directed air, the provision in association with the ceilingof said passageway of an air distributing and discharge control meanswhich comprises, a frame-like structure in the form of a grate providedwith a plurality of spaced bar-like members mounted therein past whichair is moved downwardly and by which air is distributed,

vanes movably mounted on said frame-like structure along opposite sidesthereof for vertical pivotal movement therethrough relative to saidbar-like members into a downwardly position projecting into saidpassageway, each of said vanes being in the form of a solid panel ofarcuate shape the outer surface of which is concave, said vanes eachbeing held at the top thereof by inwardly directed arms which at theiroutermost ends are attached to rods mounted on said frame-like structurefor reciprocal pivoting, and operating means for said vanes including asingle cable and plural pulley arrangement interconnected with said rodsfor simultaneous raising of a vane on one side of said frame-likestructure while lowering an oppositely positioned vane, said operatingmeans further including spaced pressure sensitive means positioned oneach side of said screen in said passageway to measure pressurediiferential for operational control of said operating means.

References Cited in the file of this patent UNITED STATES PATENTS1,173,555 Caldwell Feb. 29, 1916 1,279,993 Cummings Sept. 24, 19181,582,657 Andrews Apr. 27, 1926 2,015,960 Norris Oct. 1, 1935 2,043,487Norris June 9, 1936 2,077,734 Anderson Apr. 20, 1937 2,082,335 Hart June1, 1937 2,808,047 Jaye Oct. 1, 1957 2,818,059 Cayot Dec. 3, 1957 FOREIGNPATENTS 1,101,587 France Apr. 20, 1955 307,257 Switzerland Aug. 1, 1955760,890 Great Britain Nov. 7, 1956

